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Sensitivity of abyssal water masses to overflow parameterisations


Snow, K and Hogg, AM and Downes, SM and Sloyan, BM and Bates, ML and Griffies, SM, Sensitivity of abyssal water masses to overflow parameterisations, Ocean Modelling, 89 pp. 84-103. ISSN 1463-5003 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 Elsevier Ltd.

DOI: doi:10.1016/j.ocemod.2015.03.004


Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) control the abyssal limb of the global overturning circulation and play a major role in oceanic heat uptake and carbon storage. However, current general circulation models are unable to resolve the observed AABW and NADW formation and transport processes. One key process, that of overflows, motivates the application of overflow parameterisations. We present a sensitivity study of both AABW and NADW properties to three current parameterisations using a z*-coordinate ocean-sea ice model within a realistic-topography sector of the Atlantic Ocean.

Overflow parameterisations that affect only tracer equations are compared to a fully dynamical Lagrangian point particle method. An overflow parameterisation involving partial convective mixing of tracers is most efficient at transporting dense NADW water downslope. This parameterisation leads to a maximum mean increase in density in the north of 0.027 kg m-3 and a decrease in age of 525 years (53%). The relative change in density and age in the south is less than 30% of that in the north for all overflow parameterisations. The reduced response in the south may result from the differing dense water formation and overflow characteristics of AABW compared to NADW. Alternative approaches may be necessary to improve AABW representation in z*-coordinate ocean climate models.

Item Details

Item Type:Refereed Article
Keywords:overflow parameterisations;AABW, NADW; global climate models; sector model; overflow schemes
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Downes, SM (Dr Stephanie Downes)
ID Code:103135
Year Published:2015
Web of Science® Times Cited:20
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2015-09-22
Last Modified:2022-09-02

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